This invention relates to insulating glass units and laminates having sputter-coated layer systems thereon. More particularly, this invention relates to such articles which are heat treatable and are matchable with their unheat treated counterpart.
In U.S. Pat. No. 5,688,585 (having overlapping inventorship herewith) there is disclosed a significant step forward in the art of coating glass sheets used for solar management purposes which must be matchable in appearance after heat treatment with their unheat treated counterpart. In this patent it was accurately reported that, for the non-silver containing layer systems of that invention, if xcex94E was maintained below a certain minimal value no greater than about 2.0, the heat treatable, non-silver containing layer systems therein would be matchable. The subject invention constitutes an improvement upon the invention of the aforesaid ""585 patent.
In contrast to the ""585 patent, the subject invention herein provides a silver containing layer system which avails itself of the solar management advantages of silver. By the discovery that if certain parameters in addition to xcex94E are maintained within certain limits, as described below, it has now been surprisingly found that silver in rather substantial thicknesses may be employed while still achieving heat treatability and matchability if the layer systems are employed in either insulating glass units (I.G. units) or laminates (or other similar articles having two or more light transmitting substrates of glass). It is understood, of course, that a noncoated substrate as contemplated herein may be either glass or an equivalent thereof, such as a transparent plastic material. Moreover, it is a further discovery of this invention that matchability in such articles is achievable even though the coated monolithic glass substrate employed, while heat treatable, is not in and of itself matchable.
The need for matchability is well known in the glass window, door and windshield arts, as is the need for heat treatability. Glass substrates, normally sheet glass used for windows, doors, etc. are often produced in large quantities and cut to size in order to fulfill the needs of a particular situation such as a new multi-window and door office building. It is not only desirable in these buildings, but often a necessity in order to conform to various code provisions, that some of the windows and doors be heat treated (i.e. tempered, heat strengthened or bent) while others, principally to save money, need not be, and thus are not heat treated. Still further, such buildings often employ I.G. units and/or laminates for safety and/or thermal control. Obviously the units and/or laminates which are heat treated must match with (i.e. appear in color, and preferably in transmittance and reflectance as well, to be substantially the same as) the unheat treated I.G. units and/or laminates used together in the building, for architectural and aesthetic purposes. In addition, currently, such windows, doors, etc. for many commercial purposes should preferably be of a substantially neutral color, preferably tending to the blue-green side of the spectrum.
Through rigorous trial and error attempts, it has in the past been possible to achieve matchability in systems other than those of the aforesaid ""585 patent but only between two different layer systems, one of which is heat treated and the other is not. The necessity of developing and using two different layer systems to achieve matchability creates additional manufacturing expense and inventory needs which are undesirable. The aforesaid invention disclosed in the ""585 patent fulfilled a definite need in the art which overcame this problem. However, it could not, in that system, take advantage of the use of silver for its known IR reflectance properties, and still achieve its desired results.
The silver containing layer systems of the invention herein are useful in glass articles which generically may be described as an article or structure which includes at least two glass substrates in light transmitting relationship with each other. Preferred articles include architectural doors and windows, such as laminates and I.G. units, as well as, at times automotive windshields and windows.
As used herein, the term I.G. unit is synonymous with the term xe2x80x9cinsulating glass unitxe2x80x9d and is used according to its conventional and well known meaning in the art. FIGS. 2 and 4 illustrate, schematically, a typical I.G. unit contemplated for use with the coating systems of this invention. Generally speaking, as contemplated herein, I.G. units are comprised of two or more parallel, spaced sheets of glass held in spaced relationship by an appropriate frame structure. The space(s) between the two or more sheets, typically about one-half inch, either has air in it or an inert gas such as argon, or is partially evacuated. Most are provided with a desiccant within the space to prevent xe2x80x9cfogging.xe2x80x9d It is, of course, understood that FIGS. 2 and 4 are merely examples of many types of I.G. units used for thermal and/or sound insulation purposes, as contemplated by this invention.
The term xe2x80x9claminatexe2x80x9d is also well understood in the glass art and is used herein according to its well known meaning. Glass laminates normally include two or more unspaced substrates of glass (shaped or unshaped sheets of glass) which, in the instances of this invention will have at least one coating of a layer system of this invention thereon, normally but not always located at the interface of the two sheets. Such laminates may be flat structures (e.g. sheets cut to size) used in windows, doors or windshields, or bent to meet specific architectural or automotive needs. For example, FIG. 5 schematically illustrates, in generic fashion, a typical two sheet (pane) laminate used as a curved window or windshield.
By way of further background related to this invention attention is directed to the discussion of the prior art in the aforesaid ""585 patent. With respect thereto, the BOC Group, Inc. (Wolfe et al) as well as two of the inventors hereto (Messrs. Larson and Lingle) for Guardian Industries, and others have hereto reported various layer coating system (some commercial) employing metallic silver sandwiched between layers of nichrome followed by layers of Si3N4 to achieve either heat treatable or nonheat treatable solar management coating systems. Other examples of such a structure by these inventors include U.S. Pat. Nos. 5,344,718; 5,376,455; 5,514,476 and 5,770,321. The BOC Group""s well known Super E-III and Super-E IV coatings are generally referenced in U.S. Pat. Nos. 5,377,045 and 5,563,734 and exemplify such a known generic structure as well.
In this respect the above-referenced ""455 patent also achieved some degree of matchability and heat treatability in certain circumstances. Generally speaking, however, this body of prior art, as a whole, did not achieve the full degree of matchability and heat treatability desired for reliability in manufacturing while at the same time achieving durability and the desirable substantially neutral blue-green color and low U-values and/or shading coefficients desired in I.G. units and laminates.
In view of the above it is apparent that there exists a need in the art for a new layer coating system which is of a commercially acceptable color and which is also heat treatable as well as matchable when used in articles employing two or more light transmitting glass substrates in light transmitting relationship one with the other.
It is a purpose of this invention to fulfill this and other needs in the art which will become more apparent to the skilled artisan once given the following disclosure.
This invention, generally speaking fulfills the above-described needs in the art by providing certain articles which include two or more glass structures in light transmittance communication with each other and which have a unique layer system of this invention on at least one of its surfaces. In addition, this invention further provides a method of making such articles. In this respect then, this invention provides:
In a glass article having at least two glass substrates in light transmitting communication with each other and having a sputter coated heat treatable layer system on at least one of said substrates, which coated substrate is heat treated, the improvement comprising said glass article being matchable and wherein said sputter coated layer system comprises from the glass substrate on which it is coated, outwardly:
a) a layer of silicon nitride;
b) a substantially metallic layer of nickel or nickel alloy having a nickel content of at least about 10% by weight Ni, this layer being substantially free of a nitride or oxide of said metal;
c) a substantially metallic layer of silver;
d) a substantially metallic layer of nickel or a nickel alloy having a nickel content of at least about 10% by weight Ni, this layer being substantially free of a nitride or an oxide of said metal; and
e) a layer of silicon nitride; wherein said heat treated layer coating system has a visible transmittance at least about 4% greater than before it was heat treated, and wherein the relative thicknesses of said layers combine to result in said heat treated coated substrate which when viewed monolithically from the glass side of said coating has a xcex94E*ab no greater than 5.0 and a xcex94a* less than 0.8.
In another aspect of this invention there is provided, in the method of making a matchable glass article having at least two glass substrates in light transmitting communication with each other and having a heat treatable sputter coated layer system on at least one surface of a said substrate which coated substrate is heat treated, the improvement comprising the steps of:
a) sequentially sputter coating onto a surface of at least one of the glass substrates a said heat treatable layer system which comprises from the glass substrate on which it is coated, outwardly:
a layer of silicon nitride;
a substantially metallic layer of nickel or nickel alloy having a nickel content of at least about 10% by weight Ni, this layer being substantially free of a nitride or oxide of said metal;
a substantially metallic layer of silver;
a substantially metallic layer of nickel or a nickel alloy having a nickel content of at least about 10% by weight Ni, this layer being substantially free of a nitride or an oxide of said metal; and
a layer of silicon nitride; wherein the relative thicknesses of said layers combine to result in said article when viewed from a glass side having a xcex94E*ab no greater than 3.0 and a xcex94a* less than 0.7;
b) subjecting said substrate having said coating thereon to a heat treatment which increases the visible transmittance of said coated substrate by at least about 4%; and
c) thereafter fabricating said glass substrates so as to be in light transmitting communication with each other thereby to form said matchable glass article.
In certain preferred embodiments the desired color is substantially neutral but preferably is located in the blue-green quadrant as represented by both a* and b* being negative. In further preferred embodiments of this invention the glass article is a window or door formed from at least two sheets of glass and fabricated as either an I.G. unit or a glass laminate. In this respect the heat treatment employed in the preferred embodiments of this invention is selected from bending, tempering, or heat strengthening, and most preferably is tempering.